I am quite late to this but yes, it is ok to feel sad. It is important to understand your sadness. By understanding it, you can find a way to overcome it. It may take some time alone but you have every right to want that time alone. If you feel that's what will make you feel better, then go for it. I've been gone for ages here for the same reason. I just hope that you feel better. Seeing other people happy makes me happy as well. Take care!